Livestock health & welfare during recovery
Meat & Livestock Australia July 25, 2023
Airways and lungs
Look out for animals with breathing problems, which may be a result of smoke inhalation. In a study of sheep at abattoirs following the Black Summer bushfires, sheep with exposure to intense fire in the month before slaughter were 10 times more likely to have pneumonia detected at slaughter.
Meat quality
Meat quality at slaughter is affected by exposure to bushfire conditions. An investigation of Meat Standards Australia (MSA) index values found cattle from farms close to high-intensity bushfire had reduced MSA index results in the weeks following fire. Meat pH and meat colour are particularly affected, with unacceptably high pH most common in animals off pasture (grass-fed, compared to feedlot, grain-fed animals) and in animals receiving hormone growth promotants. As time passes, the effects of fire exposure on meat quality decrease.
For animals intended for slaughter in the weeks after fire, where possible avoid hormonal growth promotants and feed a diet that meets your animals’ energy requirements, including grain feeding if practical. To reduce the chance of dark cutting, retain animals for several weeks after fire on appropriate feed before sending to slaughter. Depending on your farm circumstances, meat quality may not be the highest priority and animals may need to be slaughtered sooner for practical reasons.
Immune function
Detailed investigations of immune system function from cattle on farms burnt during Black Summer showed that some animals may have reduced immune function. These effects reduce as time since the fire passes. Affected animals may have slower recovery from mild injuries and increased risk of disease. Fire-exposed stock can be retained within your farm, but you should monitor for signs of disease that require treatment. This is another reason to carefully manage your farm biosecurity during recovery.
Animal behaviour
Stress and fear from bushfire can also affect animal behaviour, although at present this is not well understood. Some producers report that their animals are unusually calm after surviving a fire, while others report that their animals are difficult to handle, especially in the initial weeks. Take care when handling stock post-fire and ensure yards are safe and structurally sound before use.
Supplementary feeding
Grain or pellets have high energy density and can be a cost-effective way to feed stock but must be fed carefully to avoid ‘grain poisoning’ (also known as grain overload or lactic acidosis). Animals that have not yet adapted to grain feeding are at risk; take extra care if you do not usually feed grain or pellets to your stock. Do a gradual, controlled introduction over at least two weeks, provide hay during the introduction to avoid gorging and maintain at least 20% roughage in the ration. Ensure automatic feeders are working correctly to avoid accidentally overfeeding. Monitor closely for shy feeders and sick animals.
Stock being fed grain or pellets are also at increased risk of the disease pulpy kidney (enterotoxaemia). A booster vaccination with 5-in-1 or similar is recommended prior to feeding grain or pellets for both sheep and cattle.
Higher than usual stocking rates for animals being fed in small areas can increase the likelihood of diseases such as pneumonia, pinkeye and salmonellosis. Irritation from dust can also contribute to lung and eye problems. Early detection and treatment can help manage these risks. If possible, minimise dust by selecting an area with clay or clay loam soils to hold stock.
Diseases
Stressed animals or animals with inadequate nutrition are more susceptible to spreading and acquiring infectious diseases. Most diseases reported in producer interviews after the Black Summer bushfires were not directly caused by the fire but were due to the combination of the preceding drought and the changes to farm management that occurred during recovery. More than half of the interviewed farmers reported disease in the months after the fire. Early detection of problems means they can be addressed and treated and further disease prevented. Specific health issues to watch for include:
- pasture or weed toxicities
- coughing, pneumonia and breathing difficulties
- eye problems, especially pinkeye
- lameness
- diseases causing abortion, including pestivirus
- salmonellosis
- misadventure or accidental injury or death
- mastitis and udder problems
- unexpected deaths.
Reproductive performance
Reproductive performance is driven by many factors including nutrition, disease and genetics. Producer interviews after the Black Summer fire season showed substantial variation in reproductive outcomes. Some farms reported reduced reproductive performance following fire. Others reported improved reproductive outcomes compared to other years, possibly due to improved nutrition from effective supplementary feeding. Long-term effects on livestock reproduction beyond the initial months after fire are unlikely except for animals with undetected scarring from burn injuries.
Before joining, assess bulls or rams for undetected damage to their testes or penis and cull affected animals. If joining in the weeks after fire, bulls or rams may have reduced fertility due to the effects of high temperatures on sperm development. These effects can last 65–70 days. Fertility beyond two months after fire would not be expected to vary substantially from a typical year with similar weather patterns. If concerned, consider increasing the ratio of bulls to cows or rams to ewes for joining.
Infectious diseases that cause early pregnancy loss or abortion can occur due to stock straying between farms, buying in new stock or returning from agistment. Be aware of pestivirus and vibriosis in cattle and campylobacter abortion in sheep causing abortion storms and low calving/lambing rates in herds that have not previously had these diseases. While not seen on every farm after fire, losses from these diseases can be very costly. Seek specific advice about how best to manage or avoid these risks on your farm, including the potential role of vaccination.
For more information on these diseases, see:
Manage the body condition of pregnant animals carefully, aiming for appropriate body condition scores at calving or lambing. If your farm is understocked, pregnant animals grazing freely may become overfat. Some understocked farms saw an increase in calving difficulties and cows requiring caesarean section following the Black Summer bushfires. Standard body condition score (BCS) targets should be used, with an upper limit of cows no more than BCS 3.5 at calving and single-bearing ewes not exceeding BCS 4 at lambing.
Consider grazing fewer paddocks at higher stocking rates, restricting access to pasture with temporary electric fencing in large paddocks, or utilising excess feed by buying additional stock to get back in business or cutting hay to replenish drought reserves.